In the electronics industry, electronic components are typically assembled by laying out electronic packages on a printed circuit board. The electronic packages conventionally available give rise to particular disadvantages. For example, conventional electronic packages have the contained semiconductor device attached to a metal leadframe. The leadframe often faces the circuit board when mounted. Consequently, the heat which must be dissipated from the semiconductor die must pass through the leadframe into the circuit board. It will be well understood that it is particularly difficult to dissipate or distribute heat via the printed circuit board.
Additionally, power semiconductor packages conventionally available have a significant "footprint" which takes up an inordinate amount of space on the circuit board, thus limiting component packing density. For example, many conventional power semiconductor packages have a tab portion of the leadframe which extends from the leadframe out past the perimeter of the molded portion of the package. This extending tab, although a heat dissipater, consumes significant space on the printed circuit board. In the past, in an effort to reduce footprint size, the size of the leadframe has been reduced. However this reduces the amount of metal mass available for absorbing and distributing energy, which in turn, limits the power and current surge capacity of the package (an important consideration in surge suppression or current surge applications).
Furthermore, the leadframe of many conventional semiconductor packages directly contacts the printed circuit board. Such a package configuration precludes the use of wave soldering. This is because the wave soldering process typically requires a non-metal portion contacting the board so that portion can be glued to the board during the soldering.
Consequently it is desirable to have a semiconductor device package that does not have the primary heat path into the circuit board, that does not have a large footprint, is compatible with all assembly reflow processes including wave soldering, and does not have limited metal mass available for absorbing and distributing energy.